technology book
40Pages

PLANETARY ROLLER SCREWS U-SCREWS TECH. BOOK

Company Introduction： Planetary Roller Screws also call Satellite Roller Screws is our main product. U-Screws as the leading manufacturer of the world's most accurate transmission control system, has focused on R&D and manufacture of the key component that provides highest acceleration and speed, heavy load, and high life time. The component we named as 「Planetary Roller Screws」has been used in wide range for military and national defense industries and aerospace industry. Along our research and development, we constantly escalated the value and innovation to the product. Except that we...

1 Introduction Planetary Roller Screws (PRS) is also called Satellite Roller Screws, Roller Screws, Planetary Lead Screws, etc., and it contains three parts: screws, nut and roller. The PRS is the best-performing transmission system among known lead screws, and it is the best choice for accuracy, life, heavy load, speed and acceleration in the existing linear motion. Its main function is to convert rotary motion into linear motion or Converting torque into axial repetitive force, and at the same time, it has better performance than existing ball screws. U-SCREWS PRS can meet different...

2-1-1 Load capacity and Life The main advantage of roller screws is their higher static and dynamic capacities compare to ball screws. The roller screws use roller thread instead of ball and the load is spread over higher number of points of contact to ensured rolling function. 2-1-2 Apply for Herz friction theory Apply to HERZ friction theory, we get the results: 3 times of static capacity and 15 times of life compare to ball screws. 2-1-3 Rigidity and Strength Due to the higher number of points of contact ensure the higher rigidity and strength. 2-1-4 Speed and Acceleration Use the...

2-1-6 Accuracy Planetary Roller screws accuracy according to DIN 69051(3 part),same as ball screws. Main follow screws 300mm length lead error Roller screws structure is strict and their accuracy is G1, G3, G5 Accuracy standard: Lead error ݑҰݑ Ұݑݰݑ calculation formula Accuracy level p: nominal lead ݰݑҰݑ Ұݑܰݑ : difference between required and nominal lead ܰݑɰݑ300ɰݑݰݑ : difference between actual and nominal lead over 300 mm ǰݑҰݑ Ұݑݰݑ : difference between actual and nominal lead over a length Lu ݰݑɰݑɰݑ°ݑ °ݑ°ݑ :travel variation over a length Lu °ݑɰݑ2ɏ0ݑݰݑ :travel variation over one revolution...

2-2 Examples of applications  Electric injection machines  Electric punching machines  Space (rocket, satellites)  Aeronautics (aircrafts, drones,

U-SCREWS Identification system 3-1 US -39x10-xxxx/xxxx-210-R3

4 U-SCREWS Select and Design 4-1 Process of select Sheet 4-1 planetary roller screw select process

4-2 Lubrication Grease is the most common lubricant for screws also can choice 100-300 Cst oil. Specially can use the dry lubrication Before shipping, roller screws are coated with a rust inhibitor. The inhibitor is not a lubricant. It may be necessary to remove the rust inhibitor before applying the lubricant in order to eliminate any risk of incompatibility.   First volume in nut is follow the catalog: Z nn . The volume of grease on shaft is using the follow formula: Z SS = 4.4 · 10-4 · d0 · l(d0: nominal diameter of the screw, l:threaded length of the screws) First volume total: Z 1 =...

4-3 Example for lubrication: US 39x20-760/1030-160-R5  mean axial load over one working cycle = 17kN  each working cycle accomplishes 32 back and forth strokes of 1000 mm (total travel of 32000 mm per working cycle)  working operation 12 working cycles per hour, 8 hours per day.  working efficiency 70 % and 5.6 hours per day.  maximum speed = 1500 r/min Suggest use grease or 100-150 Cst oil  Initial quantity of grease on shaft: Zss= 4.4 · 10-4 · d0 · l = 4.4 · 10-4 · 39 · 760 = 13 cm3 ● Initial quantity of grease in the nut Znn= 28 cm3 (see catalog of product sheet) ● Total quantity...

 Calculation of lubrication maintenance schedule tz  Zs Maximum speed = 1500 r/min From sheet 4-2: d0=39 get Zs= 680 hours  Zt The temperature measured on the nut external surface = 650C, use 800C calculate From sheet 4-2-2 :get Zt =0.65  Zm US 39x20 dynamic load carting capacity is 234 kN Fm/Co= 17/234 = 7 % From sheet 4-2-3 get Zm =1.3  tZ = Zs · Zt · Zm = 680 · 0.65 · 1.3 = 574 hours = 102 days (574/5.6= 102)  Result is within a period of 102 days, 41 cm3 of new grease must be applied, to be divided in fractions applied on a regul

5 Calculation formulas 1. Dynamic load(N) and Basic life ݐ߰ݐ10 = ߽߯ ݐְݐ ְݑܰݑ 3 ܯ߽ or ݐְݐ ְݑ߰ݑ = ߰ݐٰݐٰݑڰݑ (ڰݐ߰ݐ10 )1/3 ߰ݑ߰ݑ߰ݑ߰ݑ߰ݑ߰ݑ ߰ݐٰݐٰݑڰݑ 2. Cubic mean load(N) ڰݐٰݐ ٰݑڰݑڰݑڰݑ ڰݑڰݑ + 2ڰݐٰݐٰݑڰݑڰݑڰݑڰݑڰݑ 3 3. Critical speed of screw shaft(rpm) (a factor of 0.8 is generally recommended) ڰݑ۰ݑ ۰ݑ߰ݑ = 490 ߂ 105 ׂ (maximum speed in very short periods) 4. Speed limit of the mechanism

6. Input torque in a steady state (Nm) ݑǰݑ = ǰݐٰݐ ق װݑðݑâĎ 2000 · π · ݜ°ݜ °ݑݰݑ ðݐٰݐ ق װݑ۰ݑ ۂ װݑðݑâĎ 60000 · ݜ°ݜ °ݑݰݑ 7. Power required in a steady state(W) 9. Restraining torque(Nm) (considering system backdriving) հݜ°ݜ °ݑݰݑ 10. Nominal motor torque when accelerating(Nm) For a horizonal screw 0ݑǰݑǰݑpݑ = pݑǰݑǰݑӰݑ + Ӱݑǰݑǰݑݰݑ + ݰݑðݑâĎ [ ݐٰݐ+ ٰݑڰݑ ڰݐ߰ݐ . ߰ݜǰݜ ǰݑӰݑ . Ӱݑ԰ݑ ] 2000 Ԃ ׏ װݜ°ݜ °ݑݰݑ ݑǰݑǰݑpݑ = pݑǰݑǰݑӰݑ + Ӱݑǰݑǰݑݰݑ + ݰݑðݑâĎ [ ݐٰݐ+ ٰݑڰݑ ڰݐ߰ݐ . ߰ݑ԰ݑ ] 2000 Ԃ ׏

13. Calculate preload When no backlash is requires for all operating loads, the preload F p must be selected according to the maximum load F max ݐٰݐٰݑðݑ = ڰݐٰݐٰݑڰݑڰݑڰݑڰݑڰݑ = maximum load Only needs to be backlash-free for a specific load, preload F v should be selected according to the corresponding load F n ڰݐٰݐٰݑðݑ =

US - PRODUCT SHEET Lead

D:reference diameter Ԏ:direct efficiency Co:dynamic load ׎ׂ:indirect efficiency Coa:static load Rf xxxxxx d0: nominal diameter Sap : axial shift Is : inertia of screw In: inertia of nut Ir: inertia of roller d2: root diameter Znn:lub in nut Zss: